(1) Field of the Invention
The present invention relates to brush type cleaning apparatus and related methods, for cleaning surfaces of semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for photomasks, substrates for optical disks and the like (hereinafter referred to simply as "substrates"). In particular, a surface of such a substrate is cleaned while the substrate is spinning, with the lower end of a brush touching or slightly spaced from the upper surface of the substrate surface. The invention relates also to methods of attaching and detaching the brushes to/from brush support arms.
(2) Description of the Related Art
A conventional cleaning apparatus of this type includes, for example, a brush attached to a distal end of a swing arm and standing by in a position outwardly of an outer edge of a substrate supported for. With swings of the swing arm, the brush is movable between the standby position and the center of a substrate surface. The brush is rotatable relative to a distal end of the swing arm.
According to this conventional apparatus, the substrate is cleaned as follows. First, the swing arm is swung forward to move the brush from the standby position to the center of the substrate surface. Then, the brush and the substrate are rotated, with the lower end of the brush touching or being slightly spaced from the substrate surface. In this state, the swing arm is swung backward to move the brush from the center toward the outer edge of the substrate surface, thereby cleaning the entire substrate surface with the brush. When the cleaning is completed, the swing arm is swung backward to return the brush to the standby position to be ready for a next substrate cleaning operation.
However, the above conventional apparatus has only one brush attached to the distal end of the swing arm and standing by in the standby position. This single brush is used to clean surfaces of substrates successively. Where, for example, different types of brushes are used for different cleaning purposes, substrates must be cleaned in the following sequence. First, a brush to be used for initial cleaning (e.g. a nylon brush) is attached to the distal end of the swing arm. A substrate is cleaned with this brush in an operation as noted above (rough cleaning). After this cleaning operation, the brush is returned to the standby position. Next, this brush is detached manually from the distal end of the swing arm, and a different type of brush (e.g. polyvinyl alcohol brush) is attached manually to the distal end of the swing arm. The substrate is cleaned with this different brush in a similar operation (finishing cleaning). That is, in this case, the brushes must be changed in the course of the substrate cleaning sequence, which imposes a great trouble upon the operator and results in a low throughput of the process.
Even where substrate surfaces are cleaned with the same type of brush, the conventional apparatus using one brush in consecutive operations wears down the lower end of the brush quickly. When the lower end of the brush is worn, the brush must be changed. In the prior art this brush changing operation is carried out manually and as a result is time-consuming and troublesome. In the conventional apparatus, as noted above, a single brush is used continually to wear down the lower end of the brush quickly and shorten a use period of the brush. Consequently, the troublesome brush changing operation must be carried out frequently.
Generally, the conventional apparatus of the prior art has the following mechanism for connecting a brush to the arm. The arm includes a bolt projecting from a coupling position thereof (where the cleaning brush is coupled). A nut is screwed to the bolt in a position at the upper end of the brush. Thus, the brush is detachably attached to the coupling position of the arm.
As described above, brushes are attached to and detached from the arm for changing the brushes to carry out different types of cleaning as, or when the life of a brush comes to an end with wear of the lower end thereof. To carry out attaching and detaching of a brush, the operator, by turning the nut of a brush attached to the arm, detaches the brush from the bolt in the coupling position of the arm. Then, the operator screws the nut of a new brush to the bolt to attached the new brush to the coupling position of the arm. In the conventional cleaning brush changing operation (i.e. attaching/detaching operation), abrasion takes place among the components since the bolt and nut are meshed together. The abrasion produces dust (particles) to recontaminate cleaned substrates.
The contamination of substrates is known to cause a low yield of products in a substrate treating process including this type of substrate cleaning. Thus, the contamination of substrate noted above can never be overlooked.